When the dispenser described above is stored in a heated area for an appreciable period or is held in a user's hand for a similar period, air in the dispenser is heated and expands. If the expansion action is sufficiently energetic, the sphere can be forced upward momentarily and liquid can be discharged even though the diaphragm has not been flexed. This accidental discharge impairs the usefulness of the dispenser for some applications. The present invention employs a different dispenser construction which eliminates accidental discharge.